Impact of viscosity modifier on asphalt properties used for bus rapid transit lanes in Chengdu

摘要

In order to find the effect of different viscosity modifier dosages on asphalt binder's performance in bus rapid transit lanes in the city of Chengdu,three different viscosity modifiers were analyzed:TAFPACK-super (TPS),high-viscosity additive (HVA) and road-sciencetechnology (RST),and four different asphalt binders were investigated through laboratory experiments.The percentages of the viscosity modifiers used were:TPS (0％,8％,10％,12％,14％ and 16％) and RST and HVA (8％ and 12％) depending on the type of asphalt binder.Technical indicators of modifier asphalt were tested through conventional and unconventional binder tests.It has been found out that only a percentage greater than or equal to 14％ TPS is reasonable to achieve the requirement set by 20,000 Pa.s for the 60 ℃ dynamic viscosity on local #70 grade asphalt.The results indicate that conventional binders did not meet the requirements of the 60 ℃ dynamic viscosity when 12％ of TPS or HVA modifiers were used.In addition,the B-type styrene-butadienne-styrene (SBS)modified asphalt binder has better viscosity balance than the A-type SBS modified when 8％ of each of the three different kinds of viscosity modifiers is used.Therefore,the B-type modified SBS thus appears to be a suitable choice in asphalt mixtures for bus rapid transit lane with the 60 ℃ dynamic viscosity.